Microelectronic devices rely on intricate patterns of electrically conductive traces and other features to achieve proper performance. Typically, the creation of such patterns involves the formation of trenches (later filled in) within a dielectric material. Such trenches may be formed, for example, by a process called laser ablation patterning in which a laser beam is used to ablate a desired pattern in the dielectric material.
Laser projection patterning (LPP) is one version of laser ablation patterning. In LPP, a synchronous scan ablation technique is preferred over a stepwise ablation technique. In a synchronous scan scheme the laser beam irradiates a pattern mask and is projected onto the work piece through projection optics having a certain magnification or demagnification ratio. The mask and the work piece are typically mounted on separate motion stages and move in opposite directions. While they move, a rectangular laser beam scans across the mask and the work piece to form a pattern strip with a length equal to the length of the rectangular beam.
A relatively high energy density is required in order to successfully ablate the dielectric material and form the pattern, thus limiting laser beam size to a degree that large area patterning is not possible without stitching together multiple sub-patterns. The ever-shrinking feature size of packaging substrates demands extremely high positioning accuracy for pattern stitching.
For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the discussion of the described embodiments of the invention. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of embodiments of the present invention. The same reference numerals in different figures denote the same elements, while similar reference numerals may, but do not necessarily, denote similar elements.
The terms “first,” “second,” “third,” “fourth,” and the like in the description and in the claims, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Similarly, if a method is described herein as comprising a series of steps, the order of such steps as presented herein is not necessarily the only order in which such steps may be performed, and certain of the stated steps may possibly be omitted and/or certain other steps not described herein may possibly be added to the method. Furthermore, the terms “comprise,” “include,” “have,” and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The terms “left,” “right,” “front,” “back,” “top,” “bottom,” “over,” “under,” and the like in the description and in the claims, if any, are used for descriptive purposes and not necessarily for describing permanent relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein. The term “coupled,” as used herein, is defined as directly or indirectly connected in an electrical or non-electrical manner. Objects described herein as being “adjacent to” each other may be in physical contact with each other, in close proximity to each other, or in the same general region or area as each other, as appropriate for the context in which the phrase is used. Occurrences of the phrase “in one embodiment” herein do not necessarily all refer to the same embodiment.